code review 5966075: cmd/gc: inline slice[arr,str] in the frontend (mostly).

src/cmd/5g/gsubr.c

 // Derived from Inferno utils/5c/txt.c
 // http://code.google.com/p/inferno-os/source/browse/utils/5c/txt.c
 //
 //      Copyright © 1994-1999 Lucent Technologies Inc.  All rights reserved.
 //      Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
 //      Portions Copyright © 1997-1999 Vita Nuova Limited
 //      Portions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com)
 //      Portions Copyright © 2004,2006 Bruce Ellis
 //      Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net)
 //      Revisions Copyright © 2000-2007 Lucent Technologies Inc. and others
@@ skipping 1176 matching lines @@
 Prog *
 gregshift(int as, Node *lhs, int32 stype, Node *reg, Node *rhs)
 {
         Prog *p;
         p = gins(as, N, rhs);
         p->from.type = D_SHIFT;
         p->from.offset = stype | reg->val.u.reg << 8 | 1<<4 | lhs->val.u.reg;
         return p;
 }
 
+
+// Generate an instruction referencing *n
+// to force segv on nil pointer dereference.
+void
+checkref(Node *n)
+{
+        Node m;
+
+        if(n->type->type->width < unmappedzero)
+                return;
+
+//      TODO lvd

[minux1, 2012/04/17 18:54:49]

void
checkref(Node *n)
{
    Node m1, m2;

    if(n->type->type->width < unmappedzero)
        return;

    regalloc(&m1, types[TUINTPTR], n);
    regalloc(&m2, types[TUINT8], n);
    cgen(n, &m1);
    m1.xoffset = 0; 
    m1.op = OINDREG;
    m1.type = types[TUINT8];
    gins(AMOVBU, &m1, &m2);
    regfree(&m2);
    regfree(&m1);
}

+}
+
 static void
 checkoffset(Addr *a, int canemitcode)
 {
         Prog *p;
         Node n1;
 
         if(a->offset < unmappedzero)
                 return;
         if(!canemitcode)
                 fatal("checkoffset %#x, cannot emit code", a->offset);
@@ skipping 858 matching lines @@
         naddr(&n2, a, 1);
         goto yes;
 
 yes:
         return 1;
 
 no:
         sudoclean();
         return 0;
 }